Last term's elimination to Real Madrid was unlucky certainly, but two campaigns in a row without reaching the quarter-final stage is unacceptable, even for Sir Alex.

This article will look at the three most significant potential weaknesses that threaten to prevent Moyes from leading his team to the Estadio da Luz.

Fix them all, or face the ire of a frustrated fanbase.

Central Midfield

Why not start with the most obvious deficiency in the makeup of the Red Devils' squad—central midfield?

Michael Carrick is a top-quality player, fully deserving of a place in the side's starting lineup, but he is not enough by himself.

The likes of Tom Cleverley and Ryan Giggs are simply not good enough at this level to be dominant forces both in Britain and abroad.

Carrick needs a partner to do the leg work.

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The term "box-to-box midfielder" is thrown around a lot these days, but the role cannot be underestimated in terms of its importance.

Some may think the team can function without muscle, but unless you've got world-class playmakers in the squad, brawn is necessary.

Luka Modric seems out of reach, so grit is the next best thing.

Whether it be Ander Herrera, Marouane Fellaini or Daniele De Rossi, there is a crying need for a new signing in this area.

Creativity

David Moyes is an undisputed proficient in organising a team's defence.

However, there is an underlying fear in Manchester that he does not possess the offensive mind to mix it with the best in Europe.

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In their previous couple of games, United have looked devoid of attacking thrust. There is no penetrative danger coming through the middle.

With the team only really threatening from wide positions, a sense of predictability creeps into their game.

It is here I declare my unabashed love for playmaker Shinji Kagawa and bemoan his unfair treatment at the hands of the coaching staff.

This man is not only good enough to be a regular, he is the potential solution to many of the problems already outlined.

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He is the link between Carrick and Van Persie, between flank and flank.

He is a nimble threat darting between the lines and can cause havoc for opposing defenders.

Let Carrick dictate; let Kagawa create.

Of course, no United fan would turn their nose up at a Mesut Ozil (proving he hasn't already completed a transfer to Arsenal by the time you're reading this), but why overlook the Japan international in the place of a sulking forward played out position?

Inexperience

Of course, inexperience wont be an issue for the majority of this United squad—many already know the glory of making a Champions League final.

Rather inexperience on the manager's part.

Europe's elite club competition will be unlike anything Moyes has ever experienced in his career.

There are few easy games in the group stage, and only top-quality opposition in the knockout round.

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He will have to be tactically astute against unfamiliar opposition and a master-motivator of the men in red.

Moyes is capable of greatness at Old Trafford. He is capable of league glory and continental success.

If the players go with him into the unknown, his way will be made significantly easier.